A remarkable region in an image is a portion of that image in which it is permitted to perform a zoom operation. That region of the image is thus accessible at a higher resolution than the rest of the image.
Techniques exist for navigating in an image stored on a server, from a client terminal connected to that server. For example, the Quicktime VR technique makes it possible among other things to zoom within an image in JPEG format. This technique is implemented in a software application available via the Internet at the address http://www.apple.com/quicktime. A description of the software is given in the work entitled “The Quicktime VR Book: Creating immersive imaging on your desktop ” by Susan A. Kitchens from Paperback editions.
Thus, by virtue of this technique, it is possible, from the client terminal, to perform zoom and translation operations in the image stored on the server. A viewing window displays the result of the navigation at the client terminal.
For this, the image is stored at a plurality of predetermined resolutions on the server. Passing from a resolution to a higher resolution is by oversampling.
In this technique, there is strictly speaking no navigation or remarkable region in the image, since it is possible to navigate in the entire image.
Furthermore, image compression techniques exist which make it possible to define regions of interest. For example, image compression according to the JPEG2000 standard makes it possible to create one or more regions of interest in the image. The encoding data of a region of interest are situated at the beginning of the compressed file. It is however not possible to limit access to certain regions.